The concept of walking with a rolling action is said to come from the Masai, an ethnic group in Kenya, who move barefoot with a particularly healthy gait. Footwear enabling this particular way of walking, even when wearing shoes, has been described in the patent application document WO01/15560A1 (PCT/CH00/00412). Further information about walking with a rolling action, in particular in the field of orthopaedics, is to be found for example in the article “MBT, Orthopädieschuhtechnik 12/2004”, pp. 22-28. MBT stands for “Masai Barefoot Technology”.
The fundamentals of walking with a rolling action are described in the aforementioned document, therefore the benefits of walking with a rolling action and its positive effects on the human organism, in particular on the spine and the joints, will not be described here.
Prior art MBT shoes are distinguished in particular by their external shape and the composition of the undersole, the outer sole or tread. Reference is made here to FIG. 8 of the drawings corresponding substantially to FIG. 1 in the above-mentioned document WO 01/15560. In this figure, the reference numeral 2 refers to the upper part of the shoe. This upper part 2 is connected to the midsole 12 via a solid and hard, but flexible insole 10 and with a bottom surface 11. The midsole 12, which has a thickness of between 0.5 and 5 cm, is curved arcuately in the side view, and is soft and elastic. The lower surface of the midsole 12 is covered by a hard, elastic outer sole 13, which forms the actual running surface of the shoe. The insole bottom surface 11 and the outer sole 13 have a convex, arcuate or circular segmental shape.
As already mentioned, the use of such shoes influences the health of the wearer in an advantageous way. However MBT shoes also have many drawbacks, and these drawbacks are hindering widespread acceptance of the shoes in the market.
Firstly, the use of the shoe requires an initial training period of at least six weeks, during which walking is difficult and not without risk, particularly during the first few days. Secondly, prior art MBT shoes are not attractive in appearance, which discourages many potential purchasers, especially women, from buying and wearing such shoes. Furthermore, even after the wearer has learned how to walk in such shoes, it is notably more difficult to walk in them in a stable fashion, particularly on hard floors.
A further disadvantage with the prior art shoes is that the outer sole wears out quickly because it is required to be thin in order for the undersole to remain flexible during walking. Repair of a worn-out or torn outer sole is often difficult and expensive, which means that the shoes must be replaced frequently. Another disadvantage is that such shoes are difficult to stack or store, because of their particular sole shape, and therefore require considerably more storage space than conventional shoes.
The object of the present invention is to retain the advantages of walking with a rolling action while at the same time overcoming the above drawbacks. It is important that the footwear of the invention differs as little as possible in external appearance from traditional shoes. In particular, an object of the invention is to enable a controlled dynamic, rolling gait by means of a sole assembly having a substantially flat underside by means of an element located in the midsole of a shoe.